Code Girls: The Untold Story of the American Women Code Breakers Who Helped Win World War II

Still, there was plenty of evidence that a real war was going on. Military officers headed many units, and enlisted men rotated in and out. Even among the soldiers, though, rank had little meaning. A lieutenant might report to a sergeant or a civilian or even to a private first class. If the officer objected, he was sent overseas. “You didn’t go by rank,” said Solomon Kullback, another early Friedman hire. “You went by what people knew.”

The same was true of women. It would be an exaggeration to say women enjoyed true parity in the Arlington Hall workforce: Among the early William Friedman hires, men like Frank Rowlett, Abraham Sinkov, and Solomon Kullback were awarded military commissions to put them on an even footing with the Army brass, but the veteran women were not similarly promoted. Even so, all of the early women—Wilma Berryman, Delia Taylor, Genevieve Grotjan—found themselves running top units. To a striking degree, Arlington Hall was what would nowadays be called a “flat” organization, an egalitarian work culture in which good ideas could emerge from any quarter and be taken seriously.

In part this was thanks to the open-mindedness of the people in charge, but it was also thanks to their desperation. In the early months of 1943, Arlington Hall struggled to make headway in one of the Pacific War’s most urgent challenges: breaking the codes of the Imperial Japanese Army. In this effort, it was Wilma Berryman and her bobby-soxer protégée, Ann Caracristi, who would make the first significant break.





During 1942 the U.S. Army and Navy had hammered out a sane division of code-breaking duties, abandoning the odd-even rivalry dating back to the Purple break. The U.S. Navy took responsibility for breaking Japanese naval codes as well as helping with the German naval Enigma. Swamped by the demands of these major enemy systems, the Navy ceded to the U.S. Army responsibility for keeping up with Purple, as well as the codes and ciphers of many enemy and neutral nations. But the Army’s toughest assignment was breaking a fiendish tangle of Imperial Japanese Army codes, which were separate from those of the Imperial Japanese Navy and—this long into the war—remained unbroken. Tackling them was a monumental task, one that for some time appeared beyond even William Friedman’s talented and experienced group.

Part of the problem, at first, had been a lack of message traffic. Prior to the war, the Imperial Japanese Army had some 2 million troops stationed in China and on the Manchurian border, but these units were close enough in proximity that they could use low-frequency, low-power transmissions, and the U.S. Army had a hard time getting radio intercepts. To break a complex enciphered code like the ones used by the Japanese military, it’s essential to have what’s known as “depth”: lots and lots of intercepted messages that can be lined up and compared. In the panicked atmosphere after Pearl Harbor, the group made a stab at a solution nonetheless. In 1941, a British colleague brought some Japanese Army intercepts to Friedman’s operation in the old Munitions Building. Friedman shut four of his staffers—Solomon Kullback, Wilma Berryman, Delia Taylor, and Abraham Sinkov—in a room, telling them not to emerge until they had broken something. The job was just too big. After about three months, Solomon Kullback stood up and shoved his desk back into the German section. “I’ve had it,” he said. The only positive outcome was that Delia Taylor and Abe Sinkov fell in love, got married, and moved into a houseboat at the wharf. Other than that, the first attempt was dispiriting and the winter of 1942 was a gloomy one.

In many ways, however, great success was the Japanese Army’s great undoing. After its stunning victories in the first half of 1942, the Japanese Army began to spread out. Millions more troops now occupied a greatly enlarged amount of territory. Japanese units fanned out over Asia and the Pacific archipelagos: China, Hong Kong, the Philippines, Thailand, Burma, Malaya, the Dutch East Indies. The Eighth Area Army concentrated around the stronghold of Rabaul, on the island of New Britain. Each unit remained tied to its home base in Japan and was obliged to send back reports on things like casualties and the need for reinforcements. As the Japanese Army got farther from Japan, radiomen increased the power of their transmissions, and this made it much more feasible to intercept them.

Soon enough, the problem at Arlington Hall was not a dearth of intercepts. Japanese Army messages began pouring in by the tens of thousands—by airmail, by cable, by teletype. The problem was that there were many systems, each complicated in its own way. In the final months of 1942 and into early 1943, the code breakers of Arlington Hall worked in a fever—painfully aware that their colleagues in the U.S. Navy had broken JN-25 and were laughing into their gold-braided sleeves at the Army’s galling lack of progress.





The Arlington Hall code breakers also knew that the situation in the Pacific was at a tipping point. In the wake of Midway, an American pushback plan was being formulated, as the fighting forces of the U.S. Army and Navy hammered out their own division of labor in the world’s biggest ocean. After much sparring, the services agreed that Admiral Chester Nimitz would be the Pacific theater commander and that the U.S. Navy under Nimitz would deploy mostly in the central and North Pacific, a huge blue-water arena where the only wisps of land were tiny atolls. Down in the southwestern part of the hemisphere, where there was more terra firma, the U.S. Army—led by MacArthur—would fight along the islands, adopting an “island hopping” strategy in which some Japanese-held islands would be assaulted with the intent of seizing airstrips and establishing overlapping zones of air power. Cut off from supplies and reinforcements, other islands would be bypassed, isolated, and allowed to wither.

Liza Mundy's books